Date: Thu, 6 Mar 1997 16:01:57 GMT From: "Jeff Duntemann" To: Multiple recipients of list Subject: Vitamin bottle coil form basics Hi gang-- Gathered my thoughts on vitamin bottles as coil forms and thought I'd summarize here. The current recycling craze has made it much easier to identify the type of plastic used in a pill or vitamin bottle. Most modern bottles have the little recycle symbol stamped on the bottom, with a number in the middle of the rounded triangle to indicate which plastic it is. The newest ones also have a short alphabetic abbreviation beneath the symbol as well. Type 1 is abbreviated PETE. Type 2 (the commonest for vitamin bottles) is HDPE. Does anyone here know what these are (long form) and what their RF characteristics are? The one to look for is type 6. This is the ham's friend, polystyrene, abbreviated PS under the symbol. As far as I know it has the best RF characteristics of any common plastic used in small bottles. (Certain types of teflon may be better but they don't make vitamin bottles out of teflon.) Of course, I've wound successful receiver coils on all kinds of odd stuff, not excluding paper towel tubes and PVC pipe fittings, and they've always worked. But PS is the best. For some reason, house-brand and off-brand "one-a-day" style multivitamins seem to come in polystyrene bottles. (I've also seen chewable C's in PS.) Safeway had a house brand in a 250-unit bottle that fit an AES octal base *perfectly*. We've since seen 250-unit generic one-a-days (little red pills) in identical PS bottles. I suspect there is one outfit happily providing no-name one-a-days to all the generic and house-brand vitamin retailers, using the identical bottles. Getting the sticky labels off vitamin bottles is a challenge. You need strong fingernails and LOTS of patience. Get a nail under one corner and pull S L O W L Y. It might take twenty minutes (really!) but you'll get a neater form that you can use for years and years. Of course, you can wind over the label and it'll still work. But I'm really anal about labels on coil forms. I've found that the Wal Mart house brand vitamins have labels that come off more easily than any of the others. The bottles are the same as anywhere. Many vitamins now come with a foil seal that leaves a foil ring around the neck of the bottle when you break it. Use a pocket knife and get rid of as much of that foil as you can. If you leave it there it becomes a shorted turn. To attach an AES black bakelite octal base to a vitamin bottle, first drill two holes on opposite sides of the pill bottle neck, then insert the base and wiggle a pencil onto the base through the holes in the neck. Then drill and tap the base for a 4-40 machine screw. BE CAREFUL drilling and tapping bakelite; it's extremely brittle and brooks no violence or excessive force. Also, don't tighten down the screws too hard once you put them in. You just want to immobilize the base in the form. You're not building a battleship. Remarkably (and non-obviously) the most miserably difficult part of assembling a regen coil is getting all six wires into the pins on the octal base! Two tips: Leave yourself LOTS of extra wire coming out of the coil form. AND: Stagger the lengths of the six wires. Don't make them all the same length. That way, you thread the longest wire through a pin, then the next longest, then the next longest, and so on, aiming only one wire at a time. Once the wires are all threaded through the pins, fasten the base to the form with the two 4-40 machine screws. Use brass screws if you can. Using #400 emery cloth, remove the enamel from the wires for about half an inch right outside each base pin. Then push about 1/8" of the stripped wire back up into the tube and solder the wires to the pins. Be careful with those wires while you're removing the enamel. Don't break 'em--or you'll have to dismantle the whole thing and maybe even remove a winding and re-wind it to give yourself sufficient leader to connect to the pin again. That's why I suggest not soldering *any* wires to their pins until *all* of them have been scraped clean. (Does anyone detect the voice of bitter experience here?) This makes a nice, tidy regen coil on a pluggable base for which we will have sockets way longer than the older 6-pin or 4-pin style. (Octal relay sockets will be with us yet for many years and are still being made.) --73-- --Jeff Duntemann KG7JF Scottsdale, Arizona